Engine speed control mechanism



May 29, 1956 Filed Oct. 16, 1952 R. R. ROBINSON 2,747,426

ENGINE SPEED CONTROL MECHANISM 2 Sheets-Sheet l INVENTOR.

fiana/a lfoA/mmv ATTORNEY y 9, 1956 R. R. ROBINSON 2,747,426

ENGINE SPEED CONTROL. MECHANISM Filed Oct. 16, 1952 2 Sheets-Sheet 2 INV EN TOR.

AT T 0RNEY United States Patent Oflice 2,747,426 Patented May 29, 1956ENGINE SPEED CONTROL MECHANISM Ronald R. Robinson, Morton, 111.,assignor to Caterpillar Tractor Co., Peoria, 111., a corporation ofCalifornia Application October 16, 1952, Serial No. 315,054

2 Claims. 01. 74--507 'This invention relates to control means for useon angine governors and the like and is disclosed herein in itsapplication to a spring balanced governor of the kind generally employedin connection with engines of the compression ignition type.

There are various applications of engines in which a certain operatingspeed is determined as ideal and there is little or no requirement foroperation at any other speed. For example, an engine employed fordriving a pump or electric generator set must operate at a given speedwhich is critical in that it is required for an exact output of fluidpumped or electrical energy generated. This speed is usually somewhatless than the maximum rated speed of the engine and for convenience maybe referred to as operating speed.

The present invention contemplates the provision of governor or speedcontrol mechanism for an engine in which a manual control lever may beaccurately set at a certain operating speed then moved to shut down position and thereafter quickly returned to precisely the same operatingposition for which it was originally set.

It is the object of the invention to provide a control for a governor orthe like with a manual control element having means for holding it in afixed position and with a vernier adjustment for varying the speed ofoperation of the engine while the lever occupies said fixed position. Afurther Object is to provide such means in a structure which will enableconvenient adjustment and will permit the control element to be freelymoved between its engine shut down position and the adjusted operatingposition. Further and more specific objects and advantages of theinvention are made apparent in the following description wherein theinvention is described in detail by reference to the accompanyingdrawings.

In the drawings:

Fig. 1 is a view in front elevation of an engine governor control and aportion of the governor mechanism controlled thereby with parts brokenaway to disclose certain features of construction,

Fig. 2 is a bottom plan view of the governor control mechanismillustrated in Fig. 1 as viewed from the line H-II in Fig. l and withparts broken away, and

Fig. 3 is a sectional view of the governor control mechanism taken onthe line IIII1I of Fig. 1 but with a portion of the governor spring andupper anchor therefore added.

To illustrate the invention, a conventional governor spring is shown atas connected in tension to a lever 11 fixed to a shaft 12. Also fixed tothe shaft is a lever 13 connected at its end with a fuel supply controlmember 14, such, for example, as the rack bar which adjusts fuel pumpsto vary the volume of fuel directed to an engine. The lever 13 carries aroller 15 engageable by a sliding thrust collar 16 which is influencedby conventional fly weights (not shown) to swing the lever 13 and rackbar 14 toward engine shut down position as the fly weights swingoutwardly in response to operating speed. The tension of the spring 10tends in the conventional manner to oppose the action of the fly weightsand maintain the engine in operation. Therefore, the engine speed iscontrolled by varying the tension of the main governor spring It To varythis tension, the upper end of the spring is anchored as by a bolt 17 toa lever 18 fixed against rotation by means (not .shown) on a shaft 19.

The shaft 19 may be rocked to vary the tension of the spring 10 by meansof a control lever which is connected with the shaft through the mediumof a case 20 having a cover 21 thereon and also through Vernieradjusting mechanism in the case. The control lever comprises a shaft 22rotatable in a suitable bore in the case and having a knurled knob 22aat one end so that it may be rotated by hand. At its inner end, theshaft 22 carries a worm 23 meshing with a Worm gear segment 24 fixedagainst rotation on the shaft 19 by a spline connection and a clampingscrew 25. Back lash between the worm and worm gear is taken up by aspring 26 and thrust cup 27 which bears against the end of the Worm 23.The spring is seated against a plug 28 tightly fitted in the end of thebore which releases the worm.

As best shown in Fig. 3, the case 20 is mounted for rotation about thehub of the worm gear segment 24 but is held against such rotation by themeshed engagement of the segment 24 with the Worm 23. The shaft 19 iscarried for rocking movement in a bearing 29 formed in a plate 30secured, as by cap screws 31, to a wall 32 partially shown and which isa part of the housing enclosing the governor mechanism.

With the mechanism thus far described, the tension of the governorspring 10 may be varied by swinging the knob 22a about the axis of theshaft 19 to rock the shaft. An 'arcuate track 33 is formed as a part ofthe plate 39 and has a latch socket 34 adjacent one of its ends. Aspring pressed latch pin 35 is mounted in a boss 36 on the case and isurged by a spring 37 into frictional contact with the track 33 overwhich it slides as the control lever is manipulated. When the controllever reaches the position corresponding to maximum rated engine speed,that is counterclockwise of the position illustrated in Fig. l, thelatch pin enters the rocket 34 and the lever is thereby locked againstfurther rocking movement in either direction. Retraction of the latchpin is accomplished by a retracting lever best shown in Figs. 1 and 2 at38. This lever is pivoted to the case as by B. pin 39 and has abifurcated end 40 embracing the latch pin for retracting it when the endof the lever is depressed. The end of the lever is conveniently arrangedfor operation by the thumb of the hand which grasps the knob 22a.

In the operation of the device thus far described to establish a lockingposition for the governor setting the engine is first started and thecontrol mechanism is moved to maximum rated speed position with thelatch pin 35 engaged in its socket 34. The speed of the engine is thenreduced by rotation of the knob 22a which, through the vernier controlafforded by the Worm and quadrant, rocks the shaft 19 and adjusts thetension of the governor spring 10 without varying the position of thecase 20 which is latched against movement. Suitably positioned pins 41in the case 20 limit the movement of the segment 24 so that it cannotmove beyond the position where it meshes with the worm. Now with therequired engine speed established, the case 20 is latched in the correctposition for producing that speed. Consequently the latch pin may bereleased and the engine shut down and, so long as the knob 22a is notrotated, the case may be returned to the same position withoutdifiiculty. When the engine is again started, it is simply necessary toswing the governor control lever to the position where it isautomatically latched for the desired operating speed.

The use of this invention obviates the necessity of reestablishing anoperating position which is frequently a tedious procedure each time theengine is started and also provides .a Vernier adjustment to be .used inthe original establishment of the operating positionf 'I claim:

t-LIIn'an engine speed control mechanism which includes a shaft to varyengine speed upon rocking motion, a worm and gear assembly associatedwith the shaft, a control'lever to rock the shaft by swinging saidassembly as :a unit, means on the control lever to rotate the worm torock the shaft while the unit, is stationary, and means to'flatc'h theassembly against swing'ingrnovement during such rotation of the wormwhereby a required engine speed ,may be established by rotation of theworm and reestablished 'by subsequent return of the assembly to itslatched position.

2L ,Inran englne speed control mechanism which includes a shaft to varyengine speed upon rocking motion,

4 g v a worm gear fixed to said shaft, a case enclosing said gear androtatable about the axis of said shaft, a lever rotatably mounted insaid Zcase, a worm on the lever meshing with said gear, and a releasablelatch to hold the case against rotation whereby said shaft may be rockedby rotating said lever while the case is latched and rocked by swingingsaid lever and case when the case is released.

7 References Cited in the file of this Patent 7 UNITED STATES PATENTS

